Power supply devices that step the input voltage up or down to a predetermined voltage by the switching operation of a semiconductor switching element included in a chopper circuit and output the resultant voltage are known. Parallel multiplex chopper devices, which include two or more such chopper circuits connected in parallel, are known. The times at which switching elements of the respective chopper circuits are turned on and off are staggered.
In such a parallel multiplex chopper device, resonance suppression control is performed to suppress LC resonance between a reactor and a capacitive load of the chopper device, but a current detection delay decreases the current response speed. This makes the resonance suppression control difficult.
Meanwhile, the output voltage by switching operation has a pulsed waveform, and the detected current waveform includes current ripples.
To reduce the influence of such current ripples of the detected current waveform, the output current is detected by sampling, and the current control cycle is synchronized with a PWM carrier signal. However, in the case where the current is detected in synchronization with the PWM carrier signal, the current detection is delayed by at least an amount corresponding to one cycle of the PWM carrier signal. The current detection delay decreases the current response speed, and this makes the resonance suppression control difficult.
A parallel multiplex chopper device has been proposed which, to reduce the influence of such current ripples, performs current control using a moving average of sampled values of the output current of each chopper circuit as detected current, and compares a command voltage calculated in the current control and a PWM carrier signal of the chopper circuit, the PWM carrier signal having a phase difference corresponding to a value obtained by dividing 360 degrees by the number of chopper circuits, to output a gate command, thus synchronizing the sampling interval with the PWM carrier signal (see Literature 1).